Regional variation of convective structure at monsoon onset across South America inferred from TRMM observations
To examine regional changes in convective organization prior to and following onset, we analyzed the Tropical Rainfall Measuring Mission (TRMM) 3B42 0.25o 3-hourly merged precipitation maps for 1998-2007. Our purpose is to characterize the variability in the organization of precipitating cloud systems, such as mesoscale convective systems, large squall line systems, and frontal cloud systems at monsoon onset. Analysis of 3B42 imagery is used to produce regional statistics of system type and organization in each 5o x 5o land box. Changes in the organization and intensity of convective systems prior to and following onset are studied regionally via the metrics of vertical radar reflectivity structure, convective and stratiform rain rates, and lightning flash count using the TRMM Precipitation Feature database (Nesbitt et al. 2000) for 1998-2007. Time series, cumulative distribution functions, and composite analysis of these metrics prior to and following onset for different regions will be presented.